Catalysts, particularly chromium catalysts, can be used in polymerization reactions. When chromium catalysts are used in polyolefin production, the valence of the chromium catalyst needs to be (II) to effect polymerization. Chromium catalysts can be supplied commercially in the trivalent state as chromium (III), which is then converted to the hexavalent state which is chromium (VI). The chromium (VI) is then reduced to chromium (II).
Converting the valence of the chromium from (III) to (VI) can be achieved in batch processes that use large vessels subjected to thermal cycling and take relatively long periods of time to operate. The extreme temperature cycles require a relatively long period of time to cool down and heat up, which increases the time necessary to convert each batch of catalyst. A need exists for a process that can be operated efficiently without the use of extensively variant temperature cycles and that can further reduce manual aspects of the operations.